Vacuum Drying of Magnesium Hydroxide Using Steelmaking Ladle Hot Air as an Alternative Heat Source

The growing application of magnesium in strategic industries underscores the need for sustainable and energy-efficient routes for producing high-purity magnesium compounds. In this study, a vacuum drying system was designed and fabricated to enable the recovery of magnesium hydroxide from desalination effluent, and its drying performance was evaluated. Experiments were carried out at three operating pressures (۰.۱۰, ۰.۰۵, and ۰.۰۲ bar) and three temperatures (۱۵۰, ۲۱۰, and ۲۵۰°C), utilizing hot air recovered from steelmaking ladles as an industrial waste-heat source. The results showed that reducing the operating pressure significantly decreased the drying time while enhancing the mass transfer rate. At ۰.۰۲ bar, the time required to reach the target final moisture content was markedly shorter than that at ۰.۱۰ bar, with an average reduction of approximately ۵۰%. Moreover, increasing the drying temperature from ۱۵۰ to ۲۵۰°C led to a substantial acceleration of the drying process, resulting in an overall reduction of ۶۹.۲% in total drying time. Drying kinetics were analyzed using logarithmic and two-term exponential models. Statistical evaluation revealed that the logarithmic model provided superior predictive performance, exhibiting a high coefficient of determination (R² =۰.۹۹) and lowest root mean square error (RMSE=۰.۰۱۲) across all operating conditions. Overall, this study demonstrates that the integration of vacuum drying with the utilization of steelmaking waste heat represents an efficient and sustainable approach for the recovery of magnesium hydroxide from desalination effluents, offering both technical effectiveness and industrial relevance.

کلیدواژه ها:

Drying ، Desalination brine ، Statistical Analysis ، mathematical modeling